Method of welding metals by electricity



(No Model.)

0. L. GOPPIN. METHOD OF WELDING METALS BY ELECTRICITY. No. 423,732. Patented Mar. 18, 1890.

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x f f CU v I [in EU J fnzranzfdr UNITED STATES PATENT OFFICE.

CHARLES L. COFFIN, OF DETROIT, MICHIGAN.

METHOD OF WELDINGMETALS BY ELECTRICITY.

SPECIFICATION forming part of Letters Patent No. 423,732, dated March 18, 1890.

Application filed November 12, 1389. Serial No. 330,099. (No model.)

To all whom, it may concern:

Be it known that 1, CHARLES L. COFFIN, of

I Detroit, in the county of lVayne and State of Michigan, have invented a new and useful Improvement in Welding Metals by Electricity, of which the following is a specification.

My invention relates to the method of welding metals by electricity, in which the articles to be welded are connected with the poles of a source of electricity; and it consists in creating an electrical resistance at the joint greater than that of the two articles to be welded, whereby the heating efiect of the current is increased.

The drawing is a perspective of mechanism which may be used to practice my invention.

A represents a base, on which is carried a clamp N N, insulated therefrom by suitable insulating material D.

13 represents a standard rising from base A, carrying at its upper end a head E, insulated therefrom by suitable insulating material C.

F represents a dovetail groove in head E.

H H represent the two parts of a clamp, one of which is fitted with a dovetail projection to engage with and travel in groove F.

I represents a screw-shaft swiveled in a bracket J 011 head E and engaging with a nut tapped in a projection K on one part of clamp H H.

The two parts of clamps N N and H H are drawn together by screw-bolts, as indicated in the drawing.

G and M represent the articles to be welded-for example, two bars of iron.

L represents a substance which is a conductor of electricity, but whose electrical resistance is greater than that of G and M, and for convenience L is held by an insulatinghandle. 7

P and 0 represent electrical conductors by which the clamps H H and N N are respectively connected with the opposite poles of a generator of electricity.

The operation of my invention is as follows: The articles G and M being firmly secured in the clamps H and N, the clamp H is fed down by the screwshaft I until the ends of l and M come in contact. The electric current is now passed through conductors P O, clamps II N, and bars G M. If the electrical resistance of G M at their point of contact is sufficient to materially impede the passage of the available current, the ends of G and M will be heated; but if the electrical resistance of G and M at their point of contact is sufficiently low to permit the ready passage of the available current no heating eifect, or only slight heating effect, will be produced, and G and ill cannot be welded by this method. At this point my invention comes into play. The material L, which may be platinum or any conductor of electricity having a greater electrical resistance than G and M at their point of contact, is laid upon the end of M, and the end of G is brought into contact with the upper surface of L. The current being turned on, L becomes heated and heats the ends of G and M. G and M become. hot their electrical resistance increases, and thus increases the heating eiiect of the current, until finally a welding heat is attained, and the weld is completed by pressing G against M by means of a screw-shaft I. L may be withdrawn (by slightly raising G) at any time after the ends G and M become hot enough to oifer sufficient resistance to the passage of the current; or, if it is a substance of little value, which will volatilize or become alloyed with the metal being treated at or below a welding heat, it may be permitted to volatilize or become alloyed, and G and M then brought into contact. This process admits welding large masses by a current of insufficient power or volume to heat the materials in the ordinary mode, and the interposed material L may also be used as a reducer of the local heating effect of the current by carrying the extreme heat itself and gradually bringing the materials to be welded to the desired heat.

lVhat I claim as my invention, and desire to secure by Letters Patent, is

1. The herein-described process of welding metals electrically, consisting in interposing between the surfaces to be welded a conductor of greater electrical resistance than the materials being operated upon, and pass- As the ends ing the electric heating-current through the said materials and the conductor, substantially as described.

2. The herein-described process of welding metals electrically, consisting in bringing the surfaces to be Welded in contact With a conductor of greater resistance, passing heatingcurrents through the articles to be welded and the interposed conductor, removing said interposed conductor and completing the weld [o by pressure.

CHARLES L. COFFIN.

\Vitnesses:

CYRUS E. LOTHROP, GERTRUDE ANDERSON. 

